Method of making battery-depolarizers.



lVI. E. HGLIVIES. METHOD 0F MAKING BATTERY DEPOLARTZERS.

APPLICATION FILED AUG-25.1913.

Patented Apr. 10, 1917.

'MAJDR E. HTJLMES BI I a HJW A afm/Ey MMJON n. MoLMs, or rnxnvvoon, OHr'o,-5Ass1GNoN To NATIONA'I. CARBON COMPANY,

' or CLEVELAND, OHIO, A CORPORATION or NNW JERSEY.-

' METHOD or MAKING NA'.irERY-imronenranas.

recrear To all whom t may concern.'

Be it known that I, MAJOR E. HOLMES, a citizen of the United States', residing at Lakewood, in the county of Cuyahoga and 5 State of hio, haue invented acertam new and useful improvement in Methods of'-l Making Battery-Depolarizers, of which the following is a full, clear, and exact, description. e

vThis invention relates to depolarizers for use especially in dry batteries, and 'more particularly in' that type of dry batteries, known as midget cells. Since cells of this type are subjected to very severe current drains',- 1.5

the depolarizer must be very eliicient. For this reason, the ordinary izer vis not satisfactory.

lin my co-pending applicationl led November 21st,. 1912, Serial No. 732,615, I

ing manganese peroxid-by chemically pre# cipitating the same and subjecting it to fursite or other form of oxidizing agent hasbeen mixed with vpulverized graphite, or carbon, before being packed in the dry cell around the carbon electrode. Sincesuch a mixture is obtained by purely mechanical means, vit is difiicult to obtain a uniform distribution of the depolari'zer amongl the graphite particles; To secure -best results, with such a mechanical mixture, a man- 'ganese peroxid particle' should lie adjacent each particle of graphite, or carbon in the mix. The-current passing from the electro# j' lyte to the particles of graphite, orcarbon,

liberates hydrogenr and if a particle of the depolarizer were 'located at eachplace where the current enters the carbon particles, it would be in position to give up its oxygen to combine with the liberated hydrogen and prevent the polarization of the battery.

If the manganese vperoxid isjprecipitated on each of the graphite or carbon particles or in the pores of the same, the depolarizer since it exists at the exact' surface where the hydrogen ions are liberated.-

Specivication'of Letters Patent I pyrolusite depolarl have disclosed and claimedja process of mak-v potassium chlorid is admitted to the-mixture.

is'even'better situatedfto give up its oxygen' precipitated around and in ,the graphitepar;

ticles may 'varybut I' will describe the process which'I have found to be eflicient.

ratehteu am. 1o, mit. Application filed August 25, 1913. Serial No. 786,366. i f

The single figure of the drawing illus-Iv trates a simple apparatus for the carrying out ofthe process and for producing the'de` 60 polarizerto be used in dry cells.

I have found v'that if manganese peroxid lis precipitated from hot solutions, it is better ittedfor 'a battery depolarizer than if precipitated from c'ld solutions. 1n the apparatus disclosed., means is therefore used topkeep the 4solutions in al-heated state. A solution of manganese chlorid 1: in thebarrel 2, and a solution of potassium permangainate 3 in the barrel 4' are maintainedin a heated -condition byV thel steam issuing barrel 11 containing pulverized graphite', vwhich may be mixed with a liquid such as wateror it may be first placed in the barrel in a dry condition and later mixed with i permanganate solution from 'bar- 1 rel 4:

whichfisfin the neighborhood of the boiling the permanganate. and suspended graphite When the potassium permanganate solu- -tion .3 is `heatedto thecorrect temperature point offwater, valve 10 is opened and vthe solution is admitted to the barrel 11. Steam is thenadmitted through pipe 12 to keep' B5 in a heated condition, and also to keep" the s 'graphitethorghly mixed in the solution.

When the permanganate has had suiiicient vtime tti/thoroughly soak into the graphite particles, 'valve 9 is opened and manganese Thls immediately causes a reaction 1n accordance 'with the following equation:

5Mno2.hH,.o+ 2Ko1+4HC1. The manganese peroxid in the hydrated form is precipitated-out on the surfaceof eachgraphite particle and in the pores-of the same. Some of the manganeseperoxidl is of course, precipitated in the solution di'- rect, falling down as particles separate from.

the' graphite. However, sufficient solution 70 through the pipes 5 and 6, the rate of flow is used t insure that the graphite particles are thoroughly coated .and permeated witl lthe precipitate.

' bottom' as shown in the figure, and then the plug 16 is removed from the bottom ofthe barrel 11 to discharge the sediment into drainage of current from it.

barrel 15. As a convenient means of controlling the plug 16, I have shown it fastened to a pivoted lever 17 detachably secured at one end by the nut and bolt 18.

The precipitate in barrel 15 is removed for further treatment such as decantation and 'washing to remove impurities while the operation is repeated in the upper portion of the apparatus. The material remaining after washing and decantation consists of graphite, or carbon, coated and permeated with hydrated manganese .peroxid which can be used immediately in dry cells as soon as dried out sufficiently if desired. The hydrated form of manganese peroxid has some advantages as a depolarizer, one of which is a high electromotive force. It has disadvantages, however, as a depolarizer, chief among which is its propensity to react with the zinc chlorid of the electrolyte to form hydrochloric acid. The liberated hydrochloric acid of course attacks the zinc electrode of the dry cell, regardless of Whether the cell is in storage or in use. A dry cell made with the hydrated form of manganese peroxid, therefore, has what is known as short shelf life as is stated in my prior application above referred to. A much bette'r depolarizer is` produced if the manganese peroxid is transferred over to the dehydrated form. The best way tobring about this change is to dry the precipitate to approximately 120v degrees C. to remove the surplus water in the mixture, and then grind it to a powdery condition. The powder which consists of graphite and manganese peroxld 1s vthen calcined at about 300 degrees C. which drives off the water of hydration, and leaves the MnO2 in a dehydrated and substantially pure form.

The grinding process may loosen some of the manganese peroxid from the graphite particles to which it had adhered, but a greater part of it still adheres thereto.

The mixture of depolarizer and graphite 1s used in the usual way around a carbon electrode in a zinc container, a sufficient amount of the usual electrolyte solution, of course, being used. I

I have found that a dry cell containing a depolarlzing mixture of this nature has great recuperative powers, and its voltage, therefore, holds up better under severe The manganese peroxid is perfectly mixed with the graphite particles and is in correct position for combining with the hydrogen formed by the electrolytic action of the battery. The uniformity of such a mix allows the oxygen required for depolarizing purposes to be given of at every part of the battery mix, assuring complete depolarization. The preceding method of preparing the depolarizer could readily be `carried on continuously, but I have described it as an intermittent process to simplify the explanation. It is, of course obvious that the manganese chlorid and potassium permanganate can be admitted to the graphite solution in the barrel 11 simultaneously.

My method of preparing a battery mix consisting of a precipitated depolarizer on and in conducting particles is not limited to the chemicals given nor is it limited to the manganese precipitate or to graphite. While manganese peroxid is generally accepted asv the best depolarizer to use with dry cells at the present time. it is, of course, permissible to use my method with other forms of depolarizers.

As an illustration of other combinations of chemicals than that given for the precipitation above, I may mention potassium permanganate and hydrochloric acid; manganese chlorid and either ammonium persulfate or sodium hypochlorite (alkaline solution). To precipitate other depolarizers on the conducting mgerial, the following may be given by way of example: sodium hydroxid and mercurio chlorid to precipitate mercuric oxid.

I have also deposited the depolarizer on' graphite by electrolytic means and the invention is` therefore, not to be restricted to the chemical means of carrying out the method, but4 is to be interpreted broadly.

The apparatus shown is only given by way of example and other forms may be used when desired.

No claim is made herein to a dry cell containing the improved mix, as the same is claimed in my copending case filed August 25. 1913, Serial No. 786,365.

Having described my invention, what I claim is:

1. The process of preparing an oxid depolarizerfwhich consists in agitating pulverized carbon in an oxidizing solution and adding a metallic salt capable of reacting with said solution to precipitate an oxid in intimate contact with the carbon particles.4 Y 2. process of preparing a battery depolarizer which consists in soaking pulverized conducting material in a solution of potassium permanganate. adding a solution of a manganese salt to precipitate man' ganese peroxid in intimate contact with the particles of said material, admitting steam prior to and during the'precipitation, and removing the precipitate from the solution.

3. The process of preparing a battery devMmmm '3f polm'izer which Vconsists in mingktogethel" rsalciriirigit to drive 0N the Waiter of hydrahot solutions of manganous chloridl mid tion. llt potassium permang'anate with pulverized iin testimony whereof, hereuht@ :rmx my 5 cipitated in intimate Contact With the prto and during thev precipitation, @moving f 'lim J. ADAMS, the precipitate from the mother'y liqiigr mid Mms J. STAJHUL.

graphite whereby manganes perom'd vis* prra'-v signature. .l

' y MAJUR E. HULMEQS.. ticles of the graphite, admitting steam prior Witnesses: f L 

